You're also using SFML in a "wrong" way then. SFML is not a framework. If I understood Laurent right, the class abstractions are not a design choice that people should rely on, but a simple way of re-using code. Obviously, the boundary calculation for sprites is fundamentally different from the calculation for texts, so there is no re-usable code here, that's why there is no abstraction for it.
If you need abstractions like the one you mentioned, you should design your own framework that uses SFML, not one that builds on it.